Systems and methods for video transmission

ABSTRACT

A system and method for providing video signals wherein the video signals from a single video source may be separately passed over two different transmission paths. Each transmission path includes an encoder, a communications channel and a decoder. The output of each communications path at the decoder provides the video signals and an alarm signal. The alarm signal indicates an error or disruption of the video signals over the corresponding communications path. The outputted video and alarm signals are provided to a video protection switch (VPS) device which provides the video signal from the second transmission path if the alarm signals indicates an error or disruption in the first transmission path. In one embodiment, the VPS has multiple switches, one for each of plural video sources, and a redundant switch and protection ports. The redundant switch and protection ports may be connected to receive the video and alarm signals if one of the switches in the VPS fails.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/146,522, filed May 14, 2002 by William C. Coufal et al. and entitled,“Systems and Methods for Providing Redundant Back-up to a VideoTransmission System”, which application claims the benefit of U.S.Provisional Application No. 60/359,033, filed Feb. 22, 2002 by WilliamC. Coufal et al. and entitled “Systems and Methods for ProvidingRedundant Back-Up to a Video Transmission System,” the entiredisclosures of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to a system and method forproviding redundant back-up to a video transmission system, and moreparticularly to a video changeover switch that can switch a video signalfrom primary equipment to back-up equipment upon the failure of theprimary equipment.

A contemporary video broadcasting system is illustrated in FIG. 1. Here,video signals from multiple video sources 130 (130-1 through 130-N) aretransmitted to an editing location 105 through transmission equipment100. In a typical system, transmission equipment 100 encodes the videosignals and then transmits them over a communication path or channel(e.g., a fiber optic or electrical channel). Finally, the signals aredecoded prior to entering editing location 105. At editing location 105,all of the signals from video sources 130 are tested, edited and/ormixed to produce one video signal that contains the best or preferredfootage from the video sources. The edited video signal is thenbroadcast to viewers, for example, from a broadcast site 110. Viewersdesiring to watch the broadcast receive the edited video signal with areceiver 115 and watch the broadcast with a television or other suitablevideo device. As one skilled in the art will appreciate, receiver 115can be an antenna at a person's house, the TV itself, or any suitablereceiver at a head-end of a cable provider.

During high profile broadcasting events (e.g., the Super Bowl or theOlympics) it is important for the broadcaster to avoid any disruption inthe broadcast signal. Transmission interruptions can causeembarrassment, loss of income and ill will for the broadcaster. In mostsystems, a critical transmission path for the video signals is throughtransmission equipment 100. If transmission equipment 100 fails, thesignal being broadcast to the viewers may be lost. Possible transmissionequipment 100 failures include the loss of power in the encoders ordecoders, failure of the encoders or decoders themselves, loss of signalin the channel due to channel failure, or the like. Thus, there is aneed in the art for overcoming possible failures in transmissionequipment 100 to prevent loss of the video signal to editing location105.

BRIEF SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a system andmethod for providing a video delivery system with a redundant back-up isprovided.

A more complete understanding of the present invention may be derived byreferring to the detailed description of preferred embodiments andclaims when considered in connection with the figures.

BRIEF DESCRIPTION OF THE DRAWINGS

In the Figures, similar components and/or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label with a second label thatdistinguishes among the similar components. If only the first referencelabel is used in the specification, the description is applicable to anyone of the similar components having the same first reference labelirrespective of the second reference label.

FIG. 1 is a block diagram of one embodiment of a video transmissionsystem currently known in the art;

FIG. 2 is a block diagram of one embodiment of a video transmissionsystem, in accordance with the present invention;

FIG. 3 is a block diagram of the video transmission system of FIG. 2having a plurality of video sources; and

FIG. 4 is a block diagram of one embodiment of a video protection switchthat can be used in the video transmission systems of FIGS. 2 and 3.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to a system and method forproviding redundant back-up to a video transmission system, and moreparticularly to a video changeover switch that can switch a video signalfrom primary equipment to back-up equipment upon the failure of theprimary equipment.

FIG. 2 illustrates one embodiment of a video transmission system 5 inaccordance with the present invention. In the illustrated embodiment,video transmission system 5 comprises a video source 10, a firsttransmission path 12-1 and a second transmission path 12-2 through whichthe video signals from video source 10 pass, and remote from the videosource 10, a video protection switch (VPS) 30 for switching between thevideo signals passed over the two transmission paths.

Video source 10 can be any video signal producing device, such as avideo camera, a VCR, a DVD player, the Internet, a cable system, or thelike. For example, while broadcasting a basketball game, a network mayhave several TV cameras covering the game, but only one signal typicallyis broadcast to the viewers at a time. Moreover, the network may usecomputers to generate instant replays, statistical views, playerprofiles, etc. Before broadcasting a signal to the viewing public, allof the signals from the various cameras, computers and other devicescovering the game typically are transmitted to an editing location forsignal editing, switching and/or mixing. This allows the network toproduce and transmit the best footage possible for the TV broadcast.

As discussed above, the video signals from video source 10 pass throughtwo transmission paths. In one embodiment, first transmission path 12-1comprises a first encoder 15, a first transmission channel 20-1 and afirst decoder 25, and second transmission path 12-2 comprises a secondencoder 16, a second transmission channel 20-2 and a second decoder 26.

As one skilled in the art will appreciate, encoders 15, 16 can be anydevice that transforms the video signal from video source 10 into asignal that can be easily transmitted over a communication ortransmission path. For example, encoders 15, 16 may convert the videosignals into a compressed digital format, such as MPEG, MPEG2, or thelike. Similarly, decoders 25, 26 typically are devices that convert thetransmission signal back into a video signal. In one embodiment,encoders 15, 16 and decoders 25, 26 may comprise, for example, Digilink1220 encoders/decoders from Artel Video Systems, Inc., Marlborough,Mass.

Moreover, transmission channels 20 may comprise any suitablecommunication channel. In accordance with one embodiment, transmissionchannels 20 comprise high bandwidth fiber optic cable. As one skilled inthe art will appreciate, an optical multiplexer also may be used toplace more than one signal on each fiber channel, such as, for example,the MegaWav optical multiplexer from Artel Video Systems, Inc.

As discussed in more detail below, video protection switch (VPS) 30receives video signals 40 and 41 from the two transmission paths 12-1and 12-2, respectively, and produces a video output signal 45 from oneof the two input video signals 40 or 41. In addition, VPS 30 receivesalarm signals from alarm relay outputs 35 and 36 at decoders 25 and 26,respectively. Alarm relay output 35 sends an alarm signal to VPS 30 upona detection of a video signal error or failure in transmission path 12-1(e.g., errors introduced by encoder 15, transmission channel 20-1, ordecoder 25), and alarm relay output 36 sends an alarm signal to VPS 30upon a detection of a video signal error or failure in transmission path12-2. such error or alarm signals are provided in conventional decoders,such as the previously mentioned Digilink 1220 encoder/decoder). Asdiscussed below, in the event of a video signal error or failure on oneof transmission paths 12-1, 12-2, VPS 30 switches from the failingtransmission path to the back-up or other transmission path.

FIG. 3 illustrates a video transmission system 13 having a plurality ofvideo sources 10, each of which transmits video signals over twotransmission paths in a manner similar to that in transmission system 5in FIG. 2. Thus, in accordance with the embodiment illustrated in FIG.3, the first transmission path for the video signal from video source10-1 is first encoder 15-1, first transmission channel 20-1 and firstdecoder 25-1, and the second transmission path is second encoder 16-1,second transmission channel 20-2 and second decoder 26-1. Similarly, forthe video signal from video source 10-N, the first transmission path isfirst encoder 15-N, first transmission channel 20-1 and first decoder25-N, and the second transmission path is second encoder 16-N, secondtransmission channel 20-2 and second decoder 26-N.

As with the system in FIG. 2, VPS 30 generates a video output signal 45from one of the video inputs 40, 41 into VPS 30 originating from each ofthe transmission paths. Accordingly, output signal 45-1 from VPS 30 iseither video signal 40-1 originating from video source 10-1 andcommunicating through the first transmission path (encoder 15-1,transmission channel 20-1, and decoder 25-1) or video signal 41-1communicating through the second transmission path (encoder 16-1,transmission channel 20-2, and decoder 26-1), depending on which paththe VPS 30 is using. Similarly, output signal 45-N from VPS 30 is eithervideo signal 40-N originating from video source 10-N and passing throughthe first transmission path (encoder 15-N, transmission channel 20-1,and decoder 25-N) or video signal 41-N passing through the secondtransmission path (encoder 16-N, transmission channel 20-2, and decoder26-N).

This is further illustrated in FIG. 4 which provides a more detailedillustration of one embodiment of VPS 30. In the illustrated embodiment,VPS 30 receives input signals from two transmission paths for each videosource 10. That is, VPS 30 receives a first input signal 40-1 from thefirst transmission path for video source 10-1, and a second input signal41-1 from the second transmission path for video source 10-1. Similarly,VPS 30 receives a first input signal 40-2 from the first transmissionpath for video source 10-2, and a second input signal 41-2 from thesecond transmission path for video source 10-2 (and so on).

In addition to receiving inputs 40, 41 from the two transmission paths,and more specifically from decoders 25 and 26, VPS 30 receives alarmsignals from alarm relay outputs 35 and 36 from each of decoders 25 and26, respectively. The alarm signals are provided to alarm controls 55 ofswitches 60 within VPS 30, which in turn control which switch input 65or 66 is connected to the outputs 45. In the embodiment shown, VPS 30can be pre-set so that the first input 65-1 is initially connected tooutput1 45-1 by way of the switch 60-1, and thus alarm control 55-1 isunder the control of first alarm relay output 35-1 from decoder 25-1. Ifthere is a problem with the signal input into the decoder 25-1, decoder25-1 will send an alarm signal to the VPS 30 by way of alarm relayoutput 35-1. The alarm signal causes alarm control 55-1 to change thestate of switch 60-1 to connect output 45-1 to receive the signal fromthe second input 66-1, and switch 60-1 stays in this state (i.e., input66-1 provided to output 45-1) until reset. The other switches 60 operatein the same way, each connecting switch input 65 to the output 45 unlessan alarm signal is received at one of the alarm relay outputs 35.

In FIG. 4, the VPS 30 is illustrated in operation after an alarm signalhas been received from decoder 25-2, indicating an error in the videosignal from video service 10-2 (an error in the first transmissionpath-encoder 15-2, channel 20-1, and decoder 25-2). In that event,switch 60-1 remains in the first state (input 65 connected to the out45-1), but switch 60-2 has received an alarm signal (from alarm relayoutput 35-2) and has switched to the second state (input 66-2 connectedto output 45-2).

In one embodiment, it is possible to use only the alarm relay outputs 35(the alarm relay outputs 36 are not necessary), and each switch 60 ispre-set to connect input 65 to output 45. If an alarm signal is presenton any one of the alarm relay outputs 35, the alarm control 55 for thecorresponding switch changes to connect input signal 66 to the output45, and that connection continues until the switch is manually reset tothe original position (i.e., connecting input signal 65 to the output45). In other embodiments, the alarm relay outputs 36 may be activelyused, and when any switch 60 changes to the second state (input 66connected to output 45 by virtue of an alarm signal on alarm relayoutput 35), the switch stays in that state until an alarm signal isprovided at the corresponding alarm relay output 36. When that alarmsignal from alarm relay output 36 is provided to the alarm control 55,the switch is automatically changed back to the first state (input 65connected to the output 45), without the need for a manual reset.

Thus, the present invention provides means for overcoming a problem witha signal, while disrupting the transmission only momentarily, i.e. thebrief switching time during which the alarm control 55 changes the oneof the inputs 65 or 66 that is provided to output 45.

In the event of power failure, the state of the switches 60 aremagnetically retained and the switches 60 continue to connect outputs 45to the input signals connected before the power failure. Thus, thepresent invention provides a video protection switch that continues tofunction after power loss.

The VPS 30 may also be provided with protection ports 70-1, 70-2according to one preferred embodiment of the present invention seen inFIG. 4. The ports 70-1, 70-2 provide access to an extra or redundantswitch 60-P for connecting one of the inputs 40, 41 to an output 45, inthe event one of the switches 60 fails or is otherwise inoperable. Thus,if during operation it is determined that one of the outputs 45 does notoutput the correct signal, the inputs 40, 41 corresponding to thatoutput 45 may be physically switched to protection port 70-1 andprotection port 70-2, respectively. For example, if output 45-2 is notoutputting the correct signal due to a failure of switch 60-2, inputs40-2, 41-2 may be physically disconnected from input 65-2 and input66-2, respectively. The video signal inputs 40-2 and 41-2 may then bephysically connected to protection port1 70-1 and protection port 70-2,respectively. Also, first alarm relay output 35-2 and second alarm relayoutput 36-2 (if used) are connected to alarm control 55-P of switch60-P. Once connected, output 45-P will provide the signals from eitherthe first input 40-2 or the second input 41-2, depending on the state ofswitch 60-P.

There are various modifications to the present invention that will beapparent to those of ordinary skill in the art. For instance, moreredundancy may be provided by having more than two encoders and decodersper video source, the amount of channels being equal to the number ofencoders and decoder per video source. The VPS 30 could be modified toallow for more inputs per output to increase to the redundancy of thesystem. For example, three encoders and decoders per video source may beprovided with three channels to carry the signals. The VPS 30 would bemodified to have three inputs per output and to receive three alarmrelay outputs from the decoders.

Further, the VPS 30 can provide an external reset switch for each switch60 individually (or all switches 60, collectively) so that the switches60 may be reset manually at any time (reset to their original, pre-setstate).

In conclusion, the present invention provides novel systems and methodsfor providing redundant back-up of a video transmission system. Whiledetailed descriptions of one or more embodiments of the invention havebeen given above, various alternatives, modifications, and equivalentswill be apparent to those skilled in the art without varying from thespirit of the invention. Therefore, the above description should not betaken as limiting the scope of the invention, which is defined by theappended claims.

What is claimed is:
 1. A video transmission system, comprising: a videosource; a first video transmission path that receives a video signalfrom the video source and provides a first video output signal and anerror signal, the error signal having a first state when no error isdetected in the first video output signal and a second state upondetection of an error in the first video output signal; a second videotransmission path that receives a video signal from the video source andprovides a second video output signal; and a video protection switchthat receives the first and second video output signals from the firstand second video transmission paths and provides the first video outputsignal when the error signal is in the first state and providing thesecond video output signal when the error signal is in the second state,wherein the video protection switch replaces only the first video outputsignal when the error signal is in the second state, while other videooutput signals continue to be provided from the first transmission path.2. A video transmission system for carrying video signals from firstlocation to a second remote location, comprising: a video source at thefirst location; a first video transmission path in electricalcommunication with the video source, the first video transmission pathcomprising a first encoder, a first communication channel and a firstdecoder, the first decoder providing a first video output signal and analarm relay signal, the alarm relay signal reflecting a disruption inthe first video output signal; a second video transmission path inelectrical communication with the video source, the second videotransmission path comprising a second encoder, a second communicationchannel and a second decoder, the second decoder providing a secondvideo output signal; and a video protection switch at the second remotelocation, comprising: a first input for receiving the first video outputsignal from the first decoder, and a second input for receiving thesecond video output signal from the second decoder; an output; a switchconnected for receiving both the first and second video output signals,and pre-set to provide the first video output signal to the output ofthe video protection switch; and an alarm input for receiving the alarmrelay signal; wherein when the first decoder detects a disruption in thefirst video output signal in the first transmission path, the alarmrelay signal provided to the alarm input causes the video protectionswitch to provide the second video output signal at the output of thevideo protection switch, and wherein the video protection switchreplaces only the first video output signal when the error signal is inthe second state, while other video output signals continue to beprovided from the first transmission path.
 3. The system as recited inclaim 2, wherein the second decoder provides a second alarm relay signalreflecting a disruption in the second video output signal, and the videoprotection switch further comprises a second alarm input for receivingthe second alarm relay signal, and wherein when the second decoderdetects a disruption in the video signal in the second transmissionpath, the second alarm relay signal provided to the second alarm inputcauses the video protection switch to provide the first video signal atthe output of the video protection switch.
 4. The system as recited inclaim 2, wherein the video protection switch further comprises: firstand second protection inputs; a protection switch; a protection alarminput; and a protection signal output; wherein when the switch of thevideo protection switch fails, the video output signals from the firstdecoder and second decoder may be provided to the first and secondprotection inputs, respectively, and the alarm signal provided toprotection alarm input, so that the protection switch can be used toreplace the failed switch.
 5. The system as recited in claim 2, whereinthe video protection switch further comprises: an alarm controlcontrolling the switch and connected to the alarm input.
 6. The systemas recited in claim 5, wherein the alarm input further receives a secondalarm relay signal from the second decoder, and wherein after providingthe second video output signal in response to the first alarm signal,the alarm control controls the switch based on second alarm relay signalfrom the second decoder.
 7. The system as recited in claim 5, whereinafter switching in response to the received alarm relay signal from thefirst decoder, the video protection switch continues to provide thesecond video output signal at the output of the video protection switchuntil manually reset.
 8. The system as recited in claim 2, wherein thedisruption of the video signal is a failure in the first encoder, firstchannel, or first decoder.
 9. A method for transmitting video, themethod comprising: providing a first encoder and a second encoderconnected to a video source; providing a plurality of channels, a firstchannel connected to the first encoder and a second channel connected tothe second encoder; providing a first decoder and a second decoder, withthe first decoder providing an alarm relay signal, the first decoder inelectrical communication with the first encoder by way of the firstchannel and providing a first video signal from the video source, andthe second decoder in electrical communication with the second encoderby way of the second channel and providing a second video signal fromthe video source; providing a video protection switch, the videoprotection switch comprising a first and a second signal input connectedfor receiving the first and second video signals from the first andsecond decoders, an alarm input connected for receiving the alarm relaysignal from the first decoder, a signal output, and a switch controlledby the alarm relay signal; in response to receiving the alarm relaysignal, changing a state of the video protection switch from one stateproviding the first video signal at its output to a second stateproviding the second video signal at its output, wherein changing thestate of the video protection switch comprises replacing only the firstoutput signal in response to receiving the alarm relay signal, whileother video signals continue to be provided from the first channel. 10.A method for transmitting a video signal from a video source,comprising: encoding a plurality of signals from a video source;transmitting each encoded signal on a different one of a plurality ofchannels; at a remote location from the video source, decoding eachsignal separately; inputting each of the decoded signals into a videoprotection switch; outputting a first of the decoded signals from thevideo protection switch; and if there is an error in the first decodedsignal, switching the state of the video protection switch to output asecond of the decoded signals from the video protection switch, thevideo protection switch replacing only the first decoded signal, whileother video output signals continue to be provided from the firstchannel.
 11. The method as recited in claim 10, wherein the error in thefirst decoded signal is a failure in the transmission by way of thechannel or an error during encoding or decoding.
 12. A videotransmission system, comprising: video source means for providing videosignals; first video transmission path means for receiving a videosignal from the video source means and providing a first video outputsignal and an error signal, the error signal having a first state whenno error is detected in the first video output signal and a second stateupon detection of an error in the first video output signal; secondvideo transmission path means for receiving a video signal from thevideo source and providing a second video output signal; and videoprotection switch means for receiving the first and second video outputsignals from the first and second video transmission path means andproviding the first video output signal when the error signal is in thefirst state and a providing the second video output signal when theerror signal is in the second state, wherein the video protection switchmean replaces only the first video output signal when the error signalis in the second state, while other video output signals continue to beprovided from the first transmission path.
 13. The system of claim 12,wherein the video protection switch means is at a location remote fromthe video source means.
 14. The system of claim 13, wherein the firstand second transmission path means each comprise a fiber optic cable.15. The system of claim 12, wherein the video source means comprises aplurality of video sources, each video source providing a video signal,and wherein the first and second transmission path means both carry thesame video signal from each video source.
 16. The system of claim 12,wherein each of the first and second 2 transmission means comprises anencoder for encoding the video signals from the video source means, afiber optic cable for carrying the encoded signals, and a decoder fordecoding the encoded signals and providing the decoded signal to thevideo protection switch means, and wherein the decoder in the firsttransmission means provides the error signal when an error is detectedin the decoded signal.